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/*
* Copyright (c) 2018 Inria
* Copyright (c) 2012-2013, 2015 ARM Limited
* All rights reserved
*
* The license below extends only to copyright in the software and shall
* not be construed as granting a license to any other intellectual
* property including but not limited to intellectual property relating
* to a hardware implementation of the functionality of the software
* licensed hereunder. You may use the software subject to the license
* terms below provided that you ensure that this notice is replicated
* unmodified and in its entirety in all distributions of the software,
* modified or unmodified, in source code or in binary form.
*
* Copyright (c) 2005 The Regents of The University of Michigan
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met: redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer;
* redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution;
* neither the name of the copyright holders nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/**
* @file
* Describes a strided prefetcher.
*/
#ifndef __MEM_CACHE_PREFETCH_STRIDE_HH__
#define __MEM_CACHE_PREFETCH_STRIDE_HH__
#include <string>
#include <unordered_map>
#include <vector>
#include "base/sat_counter.hh"
#include "base/types.hh"
#include "mem/cache/prefetch/associative_set.hh"
#include "mem/cache/prefetch/queued.hh"
#include "mem/cache/replacement_policies/replaceable_entry.hh"
#include "mem/cache/tags/indexing_policies/set_associative.hh"
#include "mem/packet.hh"
#include "params/StridePrefetcherHashedSetAssociative.hh"
class BaseIndexingPolicy;
namespace ReplacementPolicy {
class Base;
}
struct StridePrefetcherParams;
namespace Prefetcher {
/**
* Override the default set associative to apply a specific hash function
* when extracting a set.
*/
class StridePrefetcherHashedSetAssociative : public SetAssociative
{
protected:
uint32_t extractSet(const Addr addr) const override;
Addr extractTag(const Addr addr) const override;
public:
StridePrefetcherHashedSetAssociative(
const StridePrefetcherHashedSetAssociativeParams &p)
: SetAssociative(p)
{
}
~StridePrefetcherHashedSetAssociative() = default;
};
class Stride : public Queued
{
protected:
/** Initial confidence counter value for the pc tables. */
const SatCounter8 initConfidence;
/** Confidence threshold for prefetch generation. */
const double threshConf;
const bool useRequestorId;
const int degree;
/**
* Information used to create a new PC table. All of them behave equally.
*/
const struct PCTableInfo
{
const int assoc;
const int numEntries;
BaseIndexingPolicy* const indexingPolicy;
ReplacementPolicy::Base* const replacementPolicy;
PCTableInfo(int assoc, int num_entries,
BaseIndexingPolicy* indexing_policy,
ReplacementPolicy::Base* replacement_policy)
: assoc(assoc), numEntries(num_entries),
indexingPolicy(indexing_policy),
replacementPolicy(replacement_policy)
{
}
} pcTableInfo;
/** Tagged by hashed PCs. */
struct StrideEntry : public TaggedEntry
{
StrideEntry(const SatCounter8& init_confidence);
void invalidate() override;
Addr lastAddr;
int stride;
SatCounter8 confidence;
};
typedef AssociativeSet<StrideEntry> PCTable;
std::unordered_map<int, PCTable> pcTables;
/**
* Try to find a table of entries for the given context. If none is
* found, a new table is created.
*
* @param context The context to be searched for.
* @return The table corresponding to the given context.
*/
PCTable* findTable(int context);
/**
* Create a PC table for the given context.
*
* @param context The context of the new PC table.
* @return The new PC table
*/
PCTable* allocateNewContext(int context);
public:
Stride(const StridePrefetcherParams &p);
void calculatePrefetch(const PrefetchInfo &pfi,
std::vector<AddrPriority> &addresses) override;
};
} // namespace Prefetcher
#endif // __MEM_CACHE_PREFETCH_STRIDE_HH__